Controlled current amplitude energizing system



Jan. 24, 1967 A w V|NA| 3,300,772

CONTROLLED CURRENT AMPLITUDE ENERGIZING SYSTEM Filed March 51, 1961 4 Sheets-Sheet 1 aw XOLIEGESQUBCE A 5% 1b? :7: M6 5 Ib5 FIG. 4 2 1b 4 T g Ib5 g Ib2 O 1m OOLLECTORVOLTAGE Vc LOAD LINE FIG.1 1

ATTORNEY Jan. 24, 1967 A. w. VINAL 3,300,772

CONTROLLED CURRENT AMPLITUDE ENERGIZING SYSTEM Filed March 51, 1961 4 Sheets-$heet 2 ENERGIZING vg I VOLTAGE FIG. 3 WE V9 CONDUCTION VOLTAGE T GATE VX V1 RL Gv-1 (av-2 (av-5 Gv-n f 02*1 Rxl 1 Lx1.

,. "Q 7 M f x 01-1 01-2 01-3 D1-n D2 2 Rx2 2 Lx2 02 3 Q R 3 3 (666% 3 X X VX D2 XGN R [1 n W Lxn k M J W 1 FIG. 5

A. w. VINAL 3,300,772

CONTROLLED CURRENT AMPLITUDE ENERGIZING SYSTEM Jan. 24, 1967 4 Sheets-Shee t 3 Filed March 31, 1961 FIG. 7

Jan. 24, 1967 A. w. VINAL 3,300,772 CONTROLLED CURRENT AMPLITUDE ENERGIZING SYSTEM Filed March 31, 1961 4 Sheets- Sheet 4 United States Patent 3,300,772 CONTRGLLED CURRENT AMPLITUDE ENERGIZING SYSTEM Albert W. Vinal, Owego, N.Y., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed Mar. 31, 1961, Ser. No. 99,845 18 Claims. (Cl. 340--347) This invention relates to an electrical energizing system and in particular to a new and improved selectively controlled constant current pulse amplifier.

There are many instances in the electrical arts where it is desired to pass a current pulse through a conductor. In order for the shape of the current pulse to be maintained, it is necessary that the time constant of the conductor circuit, represented by the ratio of the inductance to the resistance, be small. The most feasible method of decreasing the time constant is to cause the conductor'resistance (and the total impedance) to be large. This, of course, affects the selection of the voltage amplitude of the pulse source voltage being used to pass a current pulse through a conductor.

There are, however, many engineering applications where the use of this technique to minimize the time constant of the conductor through which the current pulse is to pass is prohibitive based on such considerations as power consumption and pulse voltage level. In still other applications, it is often desired to use a single energizing means to selectively energize one of plural conductors and at the same time preserve the shape of the current pulse as it passes through the selected conductor. As those skilled in the art know, the resistance and inductance of each of the conductors to be energized will vary regardless of the desire for the designer to maintain them the same. Where the plural conductors have different environments, it is impossible to attempt to maintain their resistance and inductance the same. Yet, it is desirable to use the same energizing means to selectively pass the same current pulse through a selected conductor of the plural conductors. One example of a practical application in which it would be desirable for a selected conductor of plural address conductors to be selectively energized by a single energizing means is in a coincident current memory array application. In many coincident current memory array applications, it is not only necessary to select one of plural address conductors for energization, but it is also necessary to pass a current pulse of constant amplitude with opposite polarities therethrough at selected times. Those skilled in the art will recognize many other practical applications having the same requirements.

Briefly, it would be highly desirable for there being a single means for energizing any one of plural conductors with a constant amplitude current pulse where the impedance of each of the conductors may differ and where the current pulse level is not dependent upon the amplitude of the energizing voltage of the selection voltage pulse source. Moreover, it would be desirable if the time constant associated with energization of the conductor was short, even though the resistance of the conductor was relatively low and its inductance relatively high. In addition, it is desirable that the energizing means be capable of driving the current pulses through the selected conductor in a bipolar manner. In the same manner that it'- is desirable to energize a conductor and pass a current pulse therethrough having an amplitude which is highly accurately controlled, it would be desirable if the amplitude of the current pulse could be controlled in accordance with electrical digital information so as to provide a conversion to electrical analog information.

It is, therefore, the primary object of the present in- 3,39%,772 Patented Jan. 24, 1967 vention to provide a new and improved selectively energized constant current pulse amplifier device.

It is still another object of the present invention to provide a new and improved energizing system for a conductor, including a selectively controlled current pulse amplifier.

It is an additional object of the present invention to provide a new and improved means for selectively energizing one of plural conductors using one constant current pulse amplifier.

It is another object of the present invention to provide an improved energizing system for a conductor wherein a bipolar current pulse may be passed therethrough with a constant amplitude even though there is a variation in the resistance and inductance of the conductor.

It is still another object of the present invention to provide a new and improved means for selectively energizing one of plural conductors with bipolar current sources having a constantamplitude despite variations of the values of the resistance and inductance between the corn ductors.

It is an additional object of the present invention to provide a new and improved means for selectively energizing a conductor with a bipolar constant current pulse having an amplitude which is representative of an electrical digital information to electrical analog information conversion.

It is another object of the present invention to provide a new and improved means for energizing a conductor with a bipolar current pulse utilizing a selectively gated energizing voltage source and a selectively gated constant current pulse amplifier at each extremity of the conductor.

The objects of the present invention are obtained by utilizing an energizing system including at least one condoctor to be energized, and a selectively gated energizing voltage source and a selectively gated constant current pulse amplifier respectively connected to mutually exclusive extremities of the conductor. Therein, the constant current pulse amplifier may comprise (either) a semiconductor (or a pentode) coupled with (either) the emitter element of the semiconductor (or the cathode of the pentode) connected to ground through a resistor. The base of the semiconductor (or the control grid of the pentode) is arranged to be selectively clamped to a control reference voltage level for determining the amount of current Which may flow in the collector of the semiconductor (or plate of the pentode). Each selectively gated voltage source is connected via its aforementioned connection to one extremity of a conductor to the collector of the semiconductor (the anode of the pentode) which is connected at the other extremity. After the selectively gated energizing voltage source is applied to the collector of the semiconductor (the anode of the pentode) through one of the conductors and the control reference voltage level is selectively applied to the base, a current is caused to pass through the con-- ductor with an amplitude determined by the reference voltage level and relatively independent of the amplitude of the energizing voltage of the source and the resistance and inductance of the conductor. Diodes may be appropriately placed in each conductor so that the selective gating of an energizing voltage source and the selective clamping of the reference voltage level may determine when a current pulse of known amplitude and polarity is passed through that conductor.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention as illustrated in the accompanying drawings.

In the figures:

FIG. 1 shows a rudimentary electrical circuit illustrating the prior art current driver problem in a conductor;

FIG. 2 shows a conductor energization arrangement according to the teachings of the present invention;

FIG. 3 shows a voltage selection gate timing chart for the purpose of illustrating the proper operation of FIG. 2;

FIG. 4 shows a plot of the'Vc versus Ic characteristic of a semiconductor configuration as shown in FIG. 2 for the purposes of explaining the operation of FIG. 2;

FIG. 5 shows an energizing arrangement according to the teachings of the present invention as applied to plural conductors; v

FIG. 6 shows a single conductor being energized so asto pass bipolar current pulses therethrough in accordance with the teachings of the present invention;

FIG. 7 shows a diode selection arrangement which maybe utilized to apply the teachings of the present invention as shown in FIG. 6 to asubstantial number of address conductors along one coordinate of the memory addressing system.

FIG. 8 shows a conductor energization arrangement according to the teachings of the present invention similar to that shown in FIG. 2 except that the semiconductor configuration is substituted therefor by a pentode configuration; and 7 FIG. 9 shows an electrical diagram of a digital-to analog converter utilizing the teachings of the present invention. v I

Referring to FIG. 1, there is shown a single address conductor havinga typical resistance RX and atypical inductance LX. Assuming that it is desired to pass a current pulse therethrough from voltage pulse source 10, the following equation would represent the instantaneous current in the conductor:

. V ri h 1 Therein, the time constant of the circuit is represented by .the ratio of thevalue of LX to the value of RX. Those. skilled in the art will recognize that the amplitude of the current pulse passed through the conductor 1 by voltage pulse source 10 will be determined by the amplitude of the voltage pulse V, the value of RX, and

the time constant of the circuit. Unless the value of,

RX is.made to be of a substantial value, the time con stant of the circuit will be so high that the waveform of the voltage pulse appliedito the conductor will not be maintained in the current pulse. In order to assure that the amplitude of the current pulse passing through the conductor 1 is maintained at a desired level and that the waveform of the current pulse. is substantially that of the voltage pulse, the amplitude of the voltage pulse must must be closely controlled and the value of the resistor RX and inductance LX appropriately selected. In an engineering embodiment requiring'the application of one pulse voltage source to one of plural conductors in a selective manner, the capability of obtaining a current pulse of constant amplitude and proper waveform is greatly decreased unless extreme care is taken in regulating the amplitude of the voltage pulse and the time con: stant of each separate conductor.

In view of the above, the teachings of the present invention, as shown in its most rudimentary form in FIG. 2, utilizes a selectively gated voltage pulse source at one extremity of a conductor 1 and a selectively gated constant current pulse amplifier at the other extremity. In FIG. 2, the selectively gated constant current pulse amplifier is shown comprising a transistor T1 having a collector, emitter and base. The collector of transistor T1 is connected to one extremity of the conductor 1 while the emitter is connected to ground through a resistor Re. Connected to the base of transistor T1 is gating terminal Gi. Also connected to the base of transistor T1 is a conductor is very similar 4 clamping device exemplified by diode D4. Connected to the remote extremity of diode D4 is a clamping voltage which limits the hereinafter mentioned gate pulse vx to a voltage level Vx. A bias voltage V2 is connected to the collector of transistor T1 via resistor RL. Diode D3 is shown clamping the collector of transistor T1 to a voltage level V1. Connected in series with the conductor 1 are two diodes D1 and D2. These diodes are used for isolation purposes when plural conductors (not shown) are also connected to the collector of transistor T1.

Normally, transistor T1 is in its nonconducting condition and no voltage is being applied .to gating terminals Gv and Gi. Voltage V2 is providing only a sufiicient amount of reverse bias to the collector of transistor T1 to maintain the inner-electrode capacity of the collector with respect to the emitter of transistor T1 in its fully charged condition as limited 'by the voltage level V1 and diode' D3. Resistor RL may also function as a characteristic impedance termination for conductor 1.

If an energizing voltage gate pulse vg, such as that shown in FIG. 3, with an amplitude Vg is applied to gating terminal Gv, the collector-to-base junction of transistor T1 becomes, i.e., remains, properly reverse biased. After a short passage of time, as shownin FIG. 3, aconduction voltage gate pulse vx is applied to gate terminal Gi. Ber

. of transistor T1 are substantially identical permitting considerable toleration to thermal environments without changing the current magnitude caused to flow in the emitter of transistor T1. Over large variations of the voltage level which energizes the collector, the collector current remains substantially constant. The impedance of the transistor looking in its collector is relatively high with respect to the'irnpedance of the single conductor shown Therefore, the time constant of the total energizing circuit is relatively low and the current pulse waveform in the i to the'conduction voltage gate waveform of FIG. 3.

Accordingly, the teachings of the present invention as shown in FIG. 2 result in a relatively ideal condition in that the current caused to pass through the conductor is substantially independent of the resistance Rx and the inductance Lx of that conductor and the magnitude Vg of the energizing voltage gate pulse vg.

Referring to FIG. 4,'there is shown a plot of the collector voltage Vc versus collector current In for transistor T1 in the configuration shown in FIG. 2. As indicated, there is a curve for each level of current in the base-emitter junction of transistor T1, to wit: Ibl, Ib2, Ib3, etc. which represent increasing increments of current. Since these curves are substantially of zero slope, variations in the pulse amplitude of the energizing voltage applied through the conductor to the collector (such as the aforementioned voltage pulse vg) do not alter the current flowing in'the collector.

The resistor connected between the emitter and ground therein has a material effect in establishing the zero slope of the family of curves shown. Variations in the slope of the load line due to variations in the impedance of the conductors do not change respectively the emitter or collector current, Ie or Ic. The energizing voltage gate pulse vg occurs in time prior to the conduction voltage gate vx, since it is desired to avoid driving the transistor T1 in saturation during the passage of a current pulse through a conductor. If the transistor is to be kept out of saturation, the cross-hatched area must be avoided. Since the Fl :3 of the pulse vg, there is no minority carrier storage in the base of transistor T1 and the emitter current of transistor T1 is the only controlling factor in determining the current pulse level transmitted through the conductor.

Referring again to FIG. 2, the current flowing in the emitter of transistor T1 may be represented by the following equation;

Re and the current flowing in the collector of transistor T1 may be represented by the following equation;

ic=iL+iRL (4) The current iL through the conductor 1 may be expressed by the following equation:

Vac V2-Vl n; RL 5 where V2 is greater than V1. As. shown by Equation 5 and assumingthat the second term of that equation does not exceed 5% of its first term, the current iL passing through the conductor is substantially determined by the the current passing through the emitter resistor Re multiplied by the current gain or. of the transistor T1, which is connected in a common collector configuration, shown in FIG. 2.

In the transistor configuration of FIG. 2, during its ON condition, the resistance of the transistor looking through the collector may be represented by the following equation:

where rd=incremental common emitter collector resistance of transistor T1 rb=base spreading and external base resistance of transistor T1 re=emitter bulk resistances of transistor T1 fl=common emitter current gain (open circuit), and

The resistance as determined by Equation 6 will always be substantial compared to the impedance of the conductor connected thereto. Furthermore, the magnitude Vg of the energizing voltage gate pulse vg is substantially independent of the current pulse level passing through the conductor providing the following equation is satisfied:

diL

dt (7) plus the voltage drops across diodes D1 and D2, if present. In FIG. 2, clamping voltage of level V1 and clamping diode D3 serve the purpose of maintaining the diodes D2 and D1 in their reverse bias condition in the absence of an energizing voltage gate pulse vg applied to gating termi-. nal Gv.

As indicated hereinabove, the purpose of diodes D1 and D2 was to provide selection for the plural conductors cooperating with the same selectively control constant current pulse amplifier. FIG. 5 shows such plural conductors connected to transistor T1 together with plural terminals. Identical identification numerals have been retained in FIG. 5 for equivalent components whenever possible. A first conductor shows resistor Rxl and inductance Lxl in series with diodes D21 and D11; the second conductor shows resistor Rx2 and inductance Lx2. in series with diodes D22 and D1-2; the third conductor shows resistor Rx3 and inductance Lx3 in series with diodes D2-3 and D1-3; the nth conductor shows resistor Rxn and inductance Lxn in series with diodes D2n and Dl-n. Accordingly, if it is desired to pass a current pulse of the same amplitude through any one of said plural conductors, 1, 2, 3, and n, an energizing voltage gate pulse vg of amplitude Vg is applied to the appropriate gate terminal Gv1, Gv2, Gv3, and Gvn, respectively. When a conduction voltage gate pulse vx is applied via terminal Gi and clamping diode D4 coincidentally with the energizing voltage gate pulse vg, a current pulse of known level is applied through the selected conductor in the same manner as described in the operation of FIG. 2. If it is desired to change the current level of any of the current pulses, the magnitude of the clamping voltage applied through the clampingdiode D4, and which controls the gate reference voltage level Vx need only be changed. For example, when the current pulses are to be used to energize the address conductors in a magnetic memory, it is often desired during memory operation to change the amplitude of the current pulses to correspond to changing requirements for magnetomotive force within the memory devices themselves. More specifically, the coercivity of magnetic memory devices comprising the memory will change with changes in the ambient or operating temperatures in the vicinity of or within the memory unit. As a result, the amplitude of the half select addressing current pulses must be changed in order that the proper selection and output signal level is maintained. For example, the clamping voltage associated with diode D4 may be made responsive to the temperature environment of a memory system so that the amplitude Vx of the clamping voltage may be appropriately changed.

As indicated hereinabove, one of the known uses for the teachings of the present invention is the current addressing system of a coincident current magnetic memory wherein the memory elements are arranged in rectangular coordinates. In these applications not only is it necessary for plural address conductors to be selectiv ly energized with current pulses of a known level, it is also important that these current pulses be bipolar in nature. FIG. 6 illustrates how the teachings of the present invention, as shown in FIG. 2, may be utilized to provide a current pulse through an address conductor with either one polarity or the other (bipolar). Therein, at each extremity of a single conductor 1, there is shown both a pulse voltage source (energizing voltage gate) and a selectively controlled constant current pulse amplifier. As before, the same and substantially identical identification numerals have been utilized in FIG. 6 as were utilized in FIGS. 2 and 5 whenever possible. For example, the transistor acting as the selectively control constant current pulse amplifier at one extremity of the conductor 1 is identified as T1 whereas the transistor of identical selectively controlled constant pulse amplifier at the other extremity of the address conductor is identified as T1. Each of these transistors has an emitter-resistance Re and Re connected between its respective emitter and a ground reference. The pulse voltage source (energizing voltage gate) shown in circuit detail and connected to gate terminal Gv+ cooperates with transistor T1 to provide a current pulse through conductor 1 having one polarity while the pulse source connected to collector gate terminal Gvcooperates with transistor T1 to provide a current pulse of known level through conductor 1 having the other polarity.

Referring now to transistor T1, it is normally in a nonconducting condition with bias voltage V2 maintaining the collector-to-base junction reverse biased so that whatever inner-electrode capacity there is between the collector and emitter of transistor T1, it remains completely charged. Voltage V2 also maintains diodes D2 and D1 reversed biased. Resistor R2 also acts as a characteristic impedance termination for conductor 1, when transistor T1 is placed in a conducting condition. However, since the base-emitter junction of transistor T1 is not normally forward biased, no significant current passes through transistor T1. The-base of transistor T1 is connected to be energized by a normally nonconducting inverter transistor T2 connected as shown. Connected to the emitter of transistor T2 is a bias voltage of level Vx. In accordance with the aforementioned descriptions of the operation of FIGS. 2 and 3, a current pulse of a first polarity will be applied to conductor 1 as a result of an energizing voltage gate pulse vg being applied to the collector of transistor T1 via Gv+ so as tomaintain the collector base junction of transistor T1 in a reverse bias condition, and at the same time, a conduction voltage gate pulse vx is applied to gate terminal Gi-tto place transistor T2 in conduction for forward biasing the base-emitter junction of transistor T1 so that it is placed in conduction. As in the operation of the circuitry of FIGS. 2 and 5, voltage level Vx determines the magnitude of the base-emitter current of transistor T1 and the amplitude of the current pulse to the conductor 1. Diode D2 is forwardly biased by the energizing voltage gate pulse applied to gate terminal Gv+, while diode D1 is reversely biased. Although the collector of transistor T1 is also reversed biased by the same voltage gate pulse vg of amplitude Vg applied to terminal Gv+, the base emitter junction of transistor T1 is not permitted to be forwardly biased and therefore remains reversed biased so that this transistor does not conduct causing no current to flow in the collector of transistor T1.

The pulse voltage source connected to the gate terminal Gv+ may be of a number of constructions while practicing the teachings ofthe present invention. Preferably, however, it is normally desired to construct thatsource so that a minimum amount of power is being consumed during that time when the pulse voltage source is in its ofi condition. Referring again to FIG. 6 and gate terminal Gv-|-, there is shown an exemplary embodiment comprising transistors T3, T4 and T5. NPN transistor T3 is connected as an inverter in a conventional manner for application of its output voltage as it appears on its collector to the base of a second inverter comprising PNP transistor T4. PNP transistor T4 is connected so that this output provides an input to NPN transistor T5 connected in an emitter follower configuration. Thecoll-ector of NPN transistor T3 is normally reversed biased by a biasing voltage source V+ bias applied thereto. The emitter-base junction of NPN transistor T3 is normally maintained in a reversed biased condition by a biasing voltage V+ applied to the emitter as shown. On the application of a voltage gate pulse to the base of transistor T3, the base-emitter junction becomes forward biased, transistor T3 conducts and causes base-emitter current to flow in transistor T4 via base coupling resistor 23. Transistor T4- has its base-emitter junction normally reversed biased by the voltage source connected thereto.

For purposes of describing how the teachings of the present invention as shown in FIG. 6 may be applied to a coincident current memory addressing system, it is convenient to associate the pulse voltage source and the pulse constant current amplifier at each extremity of the address conductor 1 together and refer to them as a driver unit comprising two terminals. For ease of explanation, it is desirable to describe two driver units differing only by the way the steering diodes D1, D2, D1 and D2 are associated therewith. Referring back to FIG. 6, one driver unit type comprising both an energizing pulse voltage source and a pulse constant current amplifier is identified by reference to two terminals Ea and la while the driver unit type operating at the other extremity of the address conductor is identified by terminals Bi and Ii.

FIG. 7 shows thirty-two address conductors which may be representative of address conductors in a memory-array for selecting a particular memory element in accordance with its location along x and/or y coordinates. Accordingly, the thirty-two address conductors shown may, by way of example, be representative of thirty-two x coordinate address conductors. To utilize the teachings of the present invention to maximum advantage, these thirty-two conductors may be arranged in groups comprising eight conductors a piece where decoupling diodes D1, D2, D1 and D2 are also utilized as a diode selection matrix. Note that the number of diodes which are desig nated D1, D2, D1 and D2 is determined by the number of conductors which are to be energized and the number of groups into which they .are divided. Duplicate identification numbers are retained on these decoupling diodes so that their function in the total system is properly identified with the description of FIG. 6 hereinabove.

In order to understand the operation of the matrix scheme in FIG. 7, assume it is desired to pass a current pulse through conductor 1 in a first direction using a pulse voltage source and a pulse constant current amplifier in the same manner as described in FIGS. 2, 5 and 6. For example, a pulse voltage source is applied to terminal Ea which acts to forward bias all of the diodes D1 connected thereto. Note that the diodes D1 which are connected to terminal Ea are those which have been grouped along with address conductors 1 through 8. In addition to forward biasing all of diodes D1 connected to address conductors 1 through 8, the pulse voltage source applied to terminal Ea also forward biases allof. the diodes D2 connected to these same address conductors. As a result, the collectors of the transistor in the pulse constant current amplifiers connected to terminal 11 through I8 are properly reversed biased so that one of the pulse constant current amplifiers connected to one of the terminals I1 through I8 need be selected to finally determine which address conductor 1-8 will have a current pulse passed therethrou-gh. Since it is desired to pass a current pulse through conductor 1, then a conduction voltage gate pulse is applied to the input of the pulse constant current amplifier connected to terminal 11 in the same manner as described hereinabove with respect to FIGS. 2, 5 and 6. As indicatedhcreina bove in connection with FIG. 3, it is important that the pulse voltage source be applied to terminal Ea before the conduction voltage gate pulse energizes the pulse constant current amplifier connected to one of the terminals 11 through I8.

On the other hand, assume it is decided to pass the current pulse through conductor 1 in the other direction. Under these conditions, the pulse voltage source connected to terminal E1 is selectively energized so that diode D1 connected to terminal E1 is a forward biased along with all of diodes D2 connected to conductors l, 9, 17 and 25. Accordingly, each of the pulse constant current amplifiers connected to terminals Ia, 1b, 10 and Id are conditioned for energization by reason of the collector base junction being reversely biased. In order for conductor 1 to be selected from that group (which includes 1, 9, 17 and 25), it is only necessary that the pulse constant current amplifier connected to terminal Ia be selectively energized after a proper time delay ,so as to derive the proper current pulse in conductor 1. Accordingly, the same diodes which were utilized in FIGS. 2, 5 and 6 to properly instrument the teachings of. the present invention may also be used as part of a diode matrix selection scheme to reduce the number of driver units equired for a memory array along each coordinate. The

grouping of the conductors is, of course, determined by the particular practical engineering application. How ever, the same general boundary conditions for optimum economy in component are the same as those in the known diode matrix selection schemes.

For example, l2'driver units have been utilized in FIG. 7 to selectively energize one of thirty-two conductors with bidirectional current pulses of precision amplitude and response time. In a typical energizing system comprising selectable x and/or y coordinates, there need '9 only be the 2 drivers. Of course, the number of selectable at coordinates need not be the same as the number of selectable y coordinates. Assuming n x selectable coordinates and m y selectable coordinates comprising a selection matrix for (nxm) unique memory locations, there need be only 2[ /n+ /m] drivers. It should be especially noted that using the drivers of FIG. 6 with the selection arrangement described in FIG. 7, there is substantially no power being dispatched in the memory address selection circuitry except during the time duration of the current pulse in the selected address conductor. During the time duration of the current pulse, the power dissipation takes place only in the drivers energizing the selected conductor.

As indicated hereinab-ove, the teachings, of the present invention may be practiced by utilizing either a semiconductor connected as shown in FIGS. 2, 5 and 6 or a pentode connected as shown in FIG. 8. Components performing the same function in FIG. 8 as in FIG. 2 have identical identification numerals. Since the pentode has five elements, it is necessary that the additional resistors and 31 be connected,- as shown, to a positive screen bias source for the purpose of properly biasing the screen grid. As is conventional, it will be noted this suppressor grid .is shown as connected to the cathode. Cathode feedback resistor 32 operates in substantially the same manner as the emitter resistor Re of FIG. 2 in providing a plate voltage-plate current characteristic which is of the same general shape as that shown in the characteristic plots of FIG. 4. As those skilled in the art know, it is the voltage of the grid with respect to the cathode in a vacuum tube that controls the level of conduction (or plate current). However, aside from that diiference, FIG. 8 operates in substantially thesame manner as FIG. 2 with the possible exception that the family of response curves for various levels of control grid voltages will not be quite as flat as those for the semiconductor circuit of FIG. 2.

Equivalent equations could be derived for the plate current and plate impedance of the pentode of FIG. 8 as those which have been derived for FIG. 2. It is emphasized, however, that the fundamental teachings of the invention remain in that a cathode feedback resistor 32 on an emitter feedback resistor Re is utilized in substantially the same manner for the same purpose. Moreover, the collector or plate energization by an energizing voltage gate is initiated at the remote terminal Gv of the conductor 1 followed by the initiation of a controlled level of conduction by controlling the current in either the base-emitter junction of transistor T1 or the voltage on the control grid pentode of FIG. 8. In each case, the level of conduction is controlled by a voltage clamping means. In each of the FIGS. 2 and '8, diode D4 and the clamping voltage of level Vx provide this function. Accordingly, in FIG. 8, a selectively gated energizing voltage source may be applied to terminal Gv at a one point in time followed by the application of a control reference voltage level to terminal Gi for the purpose of passing a current through conductor 1 having an amplitude which is determined by the reference voltage level Vx andwhich is relatively independent of the amplitude of the energizing voltage source applied to terminal Gv and the resistance and inductance of the conductor 1.

As in FIG. 6, when it is desired to pass ibipolar currents through conductor 1, a second pentode circuit operating as a constant current amplifier may be also connected to the other extremity of conductor 1 and a second energizing voltage source may be applied to the second constant current amplifier. Moreover, decoupling diodes operating in the same manner as diodes D1, D2, D1 and D2, as shown in FIG. 6, may be utilized to apply plural drivers, each driver utilizing vacuum tubes instead of transistors in a.matrix selection arrangement similarto that shown in FIG. 7.

Referring to FIG. 9, there is shown the teachings of the present invention applied to a digital-to-analog conversion application where it is desired to pass a current level through a conductor 1 having a resistance Rx and an inductance Lx in a direction and amount which is the analog representation of a digital number. In FIG. 9, identical identification numerals are retained when the function of the circuit component is identical to that discussed hereinabove with respect to FIGS. 2 and 6. By way of example, assuming it is desired to energize conductor 1 in the direction whereby the energizing voltage gate pulse vg of amplitude Vg is applied to terminal Gv+ via diode D1 so as to forward bias D2 and energize the collector of parallel transistors T1. Then, if a conduction voltage gate pulse vx of amplitude Vx is applied to the base base of one or more of the transistors T1, the current passing through the conductor 1 will be determined bywhich of the transistors T1 are conducting and the magnitude Vx of the conduction voltage gate pulse vx as limited by the respective levels of the clamping voltages VX. By appropriately scaling each of the clamping voltages VX according to the binary weightings, each transistor may be utilized to contribute a current level which is indicative of the various orders of binary significance. Thus, if particular parallel transistors T1 are selected by the application of a conduction voltage gate pulse vx applied to particular terminals Gi, in accordance with the binary number to be converted, the current passing through conductor 1 is the DC. analog of that binary number.

While the binary scaling as shown herein has been obtained by properly scaling clamp voltages VX, it should be clear that the same result could be obtained by properly scaling the emitter resistor Re of each of the transistors T1 in accordance with the binary orders of significance keeping the clamping voltage VX constant for all parallel transistors T1. The selection of the plural terminals Gi is in accordance with the binary number to be converted. When the transistors are replaced by pentodes, this same approach may be followed. When it is desired to convert a binary number to an analog current and represent the sign of the number by the direc tion of the analog current, the bidirectional feature can be obtained by utilizing parallel transistors T1 in combination with energizing voltage gate pulse of amplitude Vg, Vg applied to terminal Gvas shown. As before, the binary weightings can either be obtained by scaling the voltage VX or by scaling the emitter resistance Re or combinations of both.

While in connection with FIG. 9, terminals Gi have been described as being simultaneously selected in accordance with a binary number to be converted, it should be clear that they could be selected according to any desired voltage pulse program with time so that the amplitude and direction of the current level in the conductor 1 can be discretely selected within the programmed time interval. The pulse constant current amplifiers being connected in parallel permit selective controlling of current magnitude and the time of occurrence. FIG. 9 has been described so as to provide a digital-to-analog conversion function with respect to conductor 1. However, to show the multiplexing capability of the teachings of the present invention, additional conductors 11 and 111 are also shown in FIG. 9 connected to additional energizing voltage gate sources. Decoupling diodes operating in the same manner described hereinabove are also shown. When it is desired to select a conductor other than 1 for the passage of current of controlled magnitude and direction (and time), the energizing voltage source associated with either conductors 11 or 111 can be energized instead of that associated with conductor 1.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. An energizing system comprising a con-ductor through which a current pulse is to be passed, an energizing voltage source, a constant current pulse amplifier, said constant current pulse amplifier having at least three elements, one of said elements functioning as an output element, another of said elements functioning as a control input element, another of said elements functioning as a common element, said output element being connected to a ground reference through a feedback resistor, means for selectively clamping said control element to a conduction voltage level for driving said amplifier into conduction, said energizing voltage source being applied to said common element through said conductor through which a current pulse is to be passed, said conduction voltage level being selectively applied to said control element coincidentally with and following the application of said energizing voltage of said energizing voltage source to said common element, said conduction voltage level and resistance value of said resistor determining the output current level passing through said conductor to be energized.

2. An energizing system comprising a conductor having a first and second extremity to be energized so as to pass a bidirectional current pulse which is controlled with precision with respect to amplitude and time, a first and second energizing voltage source, a first and second pulse constant current amplifier; plural decoupling diodes, said first energizing voltage source being connected to the first extremity of said conductor through a decoupling diode, said first pulse constant current amplifier being con nected to the second extremity of said conductor through a decoupling diode, said second energizing voltage source being connected to said second extremity of said conductor through a decoupling diode, said second pulse constant current amplifier being connected to said first extremity of said conductor through a decoupling diode.

3. An energizing system comprising a conductor having a first and second extremity to be energized so as to pass a bidirectional current pulse which is controlled with pre cision with respect to amplitude and time, a first and second energizing voltage source, a first and second pulse constant current amplifier, plural decoupling diodes, said first energizing voltage source being connected to the first extremity of said conductor through a decoupling diode, said first pulse constant current amplifier being connected to the second extremity of said conductor through a decoupling diode, said second energizing voltage source being connected to said second extremity of said conductor through a decoupling diode, said second pulse constant current amplifier being connected to said first extremity of said conductor through a decoupling diode, each of said pulse constant current amplifiers having at least three elements, one of said elements of each amplifier functioning as an output element, another of said elements of each amplifier functioning as a control output element, another of said elements of each amplifier functioning as a common element, said output element of each amplifier being connected to a ground reference through a feedback resistor, means associated with each amplifier for selectively clamping said control element of said amplifier to a conduction voltage level for driving said amplifier into conduction, the energizing voltage of said first energizing voltage source being applied to the common element of said first constant current pulse amplifier through said conductor and said first energizing voltage source cooperating with said first constant current pulse amplifier to pass a current pulse through said conductor in one direction, the energy voltage of said second energy voltage source being applied to the common element of said second constant current pulse amplifier through said conductor and said second energizing voltage source cooperating with said second constant current pulse amplifier to pass a current source through said conductor in the other direction.

4. A variable impedance semiconductor device comprising: a semiconductor having a base functioning as a control input electrode, an emitter functioning as an output electrode, and a collector functioning as a common electrode; an emitter feedback resistor connecting said emitter to a ground reference; a selectable voltage source for selectively applying an energizing voltage to said collector; an electronic selectable voltage clamping means for selectively clamping said base to a conduction voltage reference level, said conduction voltage reference level being applied coincidentally with and fol-' lowing the application of said energizing voltage; an electronic voltage clamping means connected to said collector for maintaining said collector at a collector voltage reference level; the resistance value of said emitter resistor, said conduction voltage reference level applied by said electronic voltage clamping means at said base, and said collector voltage reference level provided by said voltage clamping means at said collector maintaining the current level drawn from said source by said semiconductor through said collector independent of the internal impedance of said source and the voltage level of the energizing voltage of said source during the coin cident applications of said conduction voltage reference level and said energizing voltage.

5. An energizing system comprising a conductor, an energizing voltage source, and a variable impedance in the form of current amplifier, said variable impedance consisting of a semiconductor having an emitter functioning as an output electrode, a base functioning as a control electrode, and a collector functioning as a common electrode coupled to the other end of said conductor, said emitter being connected to a ground reference through an emitter feedback resistor, means for selectively clamping said base to a reference base voltage level for forward biasing the base emitter junction of said semiconductor; a collector biasing voltage source connected to said collector for maintaining the collector base junction of said semiconductor in a slightly reverse biased condition; said energizing voltage being applied to said collector through said conductor coincidentally with the application of the reference base voltage level to said base emitter junction, said reference base voltage level determining the collector current passing through said conductor while at the same time said collector impedance as seen bysaid energizing voltage source being relatively large so as to render the current level passing through said conductor independent of the amplitude of said energizing voltage and the value of the resistance and inductance of said conductor.

6. An energizing system for plural conductors comprising plural conductors, each having a characteristic resistance and inductance, selectable pulse voltage sources corresponding in number to the number of said conductors, separate unidirectional devices, each of said de vices connecting a mutually exclusive one of said selectable pulse voltage sources to its corresponding conductor, a single selectively variable impedance in the form of a current amplifier electrically commoning one extremity of each conductor remote from its energizing source to a ground reference, said variable impedance being of a construction such as to pass a fixed level current pulse through one of said conductors on the application of a corresponding pulse voltage from its associated selectable pulse voltage source notwithstanding variations of level of said pulse voltage and the variables in the values of the characteristic conductor resistance and inductance between the selectable conductors, said selectively variable impedance comprising a semiconductor having an emitter functioning as an output electrode, a base functioning as a control input electrode, and a collector functioning as a common electrode, said emitter being connected to a ground reference through an emitter feedback resistor, means for selectively clamping said base to a reference bias voltage for forward biasing the base emitter junction of said semiconductor, a collector biasing voltage source connected to said collector for maintaining the collector base junction of said semiconductor in a slightly reverse biased condition, each of said energizing pulse voltage sources being selectively applied to said collector through its corresponding conductor coincidentally with the application of the reference bias voltage by clamping voltage source to said emitter junction, the level of said reference bias voltage determining the electrical current passing through the conductor associated with the selected pulse voltage source while at the same time said collector impedance as seen by said selected voltage source being relatively large so as to render the current level passing through said conductor independent of the amplitude of the biasing voltage of said voltage source and the value of the resistance and inductance of said conductor.

7. An energizing system comprising a conductor through which a current pulse is to be passed, an energizing voltage source, an electronic active element switch, said active element switch having at least three terminals, one of said terminals functioning as a current output terminal, the other two terminals functioning as a control input terminal and a common terminal, respectively, said output terminal being connected to a ground reference through a feedback resistor, means for selectively clamping said control terminal to a conduction voltage reference level for driving said electronic active element into conduction and determining the amount of current which may appear at said output terminal, said energizing voltage source being applied to said common terminal through said conductor through which a current pulse is to be passed, said conduction voltage level being selectively applied to said control terminal by said means for selectively clamping coincidentally with and following the application of said energizing voltage to said output common terminal, said conduction voltage level and the resistance value of said resistor determining the output current level passing through said conductor, the impedance of said'output common terminal of said active element as seen by said energizing voltage source being relatively large'so as to render the current level passing through said conductor relatively independent of the amplitude of said energizing voltage of said source and the values of the resistance and inductance of said conductor.

8. An energizing system comprising a conductor having a'first and second extremity to be energized so as to pass a bidirectional current pulse which is controlled with precision with respect to amplitude and time, a first and second energizing voltage source, a first and second pulse constant current amplifier, plural decoupling diodes, said first energizing voltage source being connected to the first extremity of said conductor through a decoupling diode, said first pulse constant current amplifier being connected to the second extremity of said conductor through a decoupling diode, said second energizing voltage source being'connected to said second extremity of said cond-uctorthrough a decoupling diode, said second pulse constant current amplifier being connected to said first extremity of said conductor through a decoupling diode, each of said pulse constant current amplifiers having at least three elements, one of said elements of each amplifier functioningas a current output element, another of said elements of each amplifier functioning as a control input element, another of said elements of each amplifier functioning as a common element, said output element of each amplifier being connected to a ground reference through a feedback resistor, means associated with each amplifier for selectivly clamping said control element of said, amplifier to a conduction voltage level for driving said amplifier into conduction, said first energizing voltage source cooperating with said first constant current pulse amplifier to pass a current pulse through said cond-uctor in one direction, said second energizing voltage source cooperating with said second constant current pulse amplifier to pass a current source through said conductor in the other direction, said first energizing voltage source being applied to said common element of said first constant current pulse amplifier through said conductor, said second energizing voltage source being applied to said common element of said second constant current pulse amplifier through said conductor, said conduction voltage level being selectively applied to said control element of said first constant current pulse amplifier coincidentally with and following the application of the energizing voltage of said first energizing voltage source to said common element of said first constant current pulse amplifier, said conduction voltage level being selectively app-lied to said control element of said second constant current pulse amplifier coincidentally with and following the application of the energizing of said second energizing voltage source to said common element of said second constant current pulse amplifier, said conduction voltage level and resistance value of said resistor associated with each constant current pulse amplifier determining the current level passing through said corresponding conductor.

9. An energizing system comprising a conductor through which a current is to be passed having a mag nitude which is commensurate with the analog of binary coded digital information to be converted, an energizing voltage source, and plural constant current pulse amplifiers corresponding in number to the number of orders of significance in the binary digital information to bev converted, each of said constant current pulse amplifiers having at least three elements, one of said elements of each amplifier functioning as a current output element, another of said elements of each amplifier functioning as a control element, another of said elements of each amplifier functioning as a common element, said output element of each amplifier being connected to a ground reference through a feedback resistor, and separate means for selectively clamping said control element of each of. said amplifiers to a conduction voltage level for driving said corresponding amplifier into conduction, said energizing voltage source being applied to said common element of each of said amplifiers through said conductor, each of said conduction voltage levels being selectively applied to the control element of its respective amplifier in accordance with the binary coded digital information to be converted, said selected conduction voltage levels being applied coincidentally with and following the application of said energizing voltage to said common elements, each of said conduction voltage levels and resistance value of the feedback resistor associated with its respective amplifier determining the output current level passing through said respective amplifier in accordance with the binary weighted order of significance associated with said respective amplifier, said conductor having thecurrent passing therethrough equal to the sum of the currents passed through said amplifiers in accordance with the analog value of the binary coded digital information to be converted.

10. An energizing system comprising a conductor through which a current is to 'be passed having a magnitude and a direction which is commensurate with the magnitude and sign of the analog of binary coded digital information to be converted, a first and second energizing voltage source, and first and second groups of plural constant current pulse amplifiers, each group corresponding in number to the number of orders of significance in the binary digital information to be converted, said conductor having a first and second extremity, and plural decoupling diodes, said first energizing voltage source being connected to said first extremity of said conductor through a decoupling diode, said first group of constant cu'rrent' enengizing voltage source being connected to said second extremity of said conductor through a decoupling diode, said second group of constant current pulse amplifiers connected to said first extremity of said conductor through decoupling diodes, each of said constant current pulse amplifiers having at least three elements, one of said elements of each amplifier functioning as a current output element, another of said elements of each amplifier functioning as a control element, another of said elements of each amplifier functioning as a common element, said output element of each amplifier being connected to a ground reference through a feedback resistor.

11. An energizing system comprising a conductor through which a current is to be passed having a magnitude and a direction which is commensurate with the magnitude and sign of the analog of binary coded digital information to be converted, a first and second energizing voltage source, and first and second groups of plural constant current pulse amplifiers, each group corresponding in number to the number of orders of significance in the binary digital information to be converted, said conductor having a first and second extremity, and plural decoupling diodes, said first energizing voltage source being connected to said first extremity of said conductor through a decoupling diode, said first group of constant current pulse amplifiers being connected to said second extremity of said conductor through decoupling diodes, said second energizing voltage source being connected to said second extremity of said conductor through a decoupling diode, said second group of constance current pulse amplifiers connected to said first extremity of said conductor through decoupling diodes, each of said constant current pulse amplifiers having at least three elements, one of said elements of each amplifier functioning as a current output element, another of said elements of each amplifier functioning as a control element, another of said elements of each amplifier functioning as a common element, said output of each amplifier being connected to a ground reference through a feedback resistor, and separate means for selectively clamping said control element of each of said amplifiers to a conduction voltage level for driving said corresponding amplifier be converted, said selected conduction voltage levels of a said group of amplifiers being applied to the respective control inputs thereof coincidentally with and following the application of the respective energizing voltage to the respective common elements thereof through said conductor, each of said conduction voltage levels and resistance value of the feedback resistor associated with its respective amplifier determining the output current level passing through said respective amplifier in accordance with the bniary weighted order of significance as sociated with said respective amplifier, said conductor having the current passing therethrough equal to the sum of the currents passed through said amplifiers in accordance with the analog value of the binary coded digital information to be converted, said first energizing voltage source and said current pulse amplifiers of said first group passing the current through said conductor in a first direction and said second energizing voltage source and second current pulse amplifiers of said second group passing the current through said conductor in a second direction opposite to said first direction.

12. An energizing system comprising a conductor through which a current is to be passed having a magnitude which is commensurate with the analog of binary coded digital information to be converted, an energizing voltage source, and plural constant current pulse amplifiers corresponding in number to the number of orders of significance in the binary digital information to be converted, each of said constant current pulse amplifiers having at least three elements, one of said elements of each amplifier functioning as a current output element, another of said elements of each amplifier functioning as a control element, another of said elements of each amplifier functioning as a common element, said output element of each amplifier being connected to a ground reference through a feedback resistor.

13. An energizing system comprising plural conductors through which is to be selectively passed a current having a magnitude which is digitally selected, each of said conductors having first and second extremities plural energiz-' ing voltage sources corresponding in number to the number of said conductors, plural decoupling diodes, each of said sources being coupled to the first extremity of a mutually exclusive conductor through a mutually exclusive one of said diodes, and plural constant current pulse amplifiers corresponding in number to the number of separate digital inputs, each of said constant current pulse amplifiers having at least three elements, one of i said elements of each amplifier functioning as a current output element, another of said elements of each amplifier functioning as a control element, another of said elements functioning as a common element, said output element of each amplifier being connected. to a ground reference through a feedback resistor, and separate means for-selectively clamping said control element of each of said amplifiers to a conduction voltage level for driving said corresponding amplifier into conduction, each of said plural energizing voltage sources being applied to the common element of each of said amplifiers through the conductor and decoupling diode associated with, each of said conduction voltage levels being selectively applied to the control element of its respective associated amplifier in accordance'with the input digital information, the selected conduction voltage levels being applied coincidentally with and following the application of one of said energizing voltage sources to said common elements, each of said conduction voltage levels and resistance value of the feedback resistor associated with its respective amplifier determining the output current level passing through said respective amplifier in accordance with the digital significance associated with said respective amplifier, said selected conductor having a current passing therethrough equal to the sum of the currents passing through said selected amplifiers in accordance with a digital input.

14. An energizing system comprising:

a predetermined number of conductors through which current pulses are to be selectively passed, each of said conductors having first and second terminal means;

first selectable energizing voltage source means for selectively applying a first energizing voltage to the first terminal means of said conductors; and

a predetermined number of current pulse first amplifiers, each of said amplifiers having at least three elements, one of said elements functioning as a control input element, another of said elements functioning as an output element, another of said elements functioning as a common element, said common element being coupled to the second terminal means of a preselected number of said predetermined number of conductors, said output element being coupled to a ground reference through a feedback resistor, and means for selectively clamping the control element to a conduction voltage level for driving the ampli-' fier associated therewith into conduction, said energizing voltage being selectively applied through said preselected number of said predetermined number of conductors to said common element, and said conduction voltage level being selectively applied to said control element coincidentally with and following the application of said energizing voltage to said common element, said conduction voltage level and resistance value of said resistor determining the output current level passing through the preselected number of said predetermined number of conductors selectively energized by said energizing voltage source means and the current amplifier associated therewith.

15. An energizing system according to claim 14 wherein said predetermined number of current pulse amplifiers is equal to one, and said predetermined number of conductors is greater than one and said reselected number of conductors is equal to at least one,

16. An energizing system according to claim 14 wherein said predetermined number of current pulse first amplifiers is greater than one, and said predetermined number of conductors is greater than one, each of the common elements of said first amplifiers being coupled to the second terminal means of the conductors of the respective preselected number of conductors associated with its respective amplifier, said last mentioned preselected number being equal to at least one.

17. An energizing system according to claim 16 further comprising:

second selectable energizing voltage source means for selectively applying a second energizing voltage to the second terminal means of said conductors; and plural current pulse second amplifiers corresponding in number to the predetermined number of said first amplifiers, each of said second amplifiers having at least three elements, one of said elements functioning as a control input element, another of said elements functioning as an output element, another of said elements functioning as a common element, each of said common elements of said second amplifiers being coupled to the first terminal means of the conductors of the preselected number of conductors associated with an exclusive one of said first amplifiers, each of said second amplifiers further comprising a feedback second resistor coupling the output element thereof to a ground reference, and second means for selectively clamping the control element thereof to a second conduction voltage for driving the second amplifier associated therewith into conduction, said second energizing voltage being selectively applied to the common element of the respective second amplifier associated therewith through the preselected number of conductors coupled thereto, and said second conduction voltage level being selectively applied to the last mentioned control element coincidentally with and following the application of said second energizing voltage to the associated common element thereof, said second conduction voltage level and resistance value of said second resistor determining the output current level passed through the preselected number of conductors associated with the respective second amplifier selectively energized by said second energizing voltage source means and the current pulse second amplifier associated therewith, said current pulse first amplifiers and said first energizing voltage. means passing the current in their associated conductors in a first direction, and said current pulse second amplifiers and said second energizing voltage means passing the current in their associated conductors in a second opposite direction. 18. An energizing system according to claim 14 wherein said predetermined number of current pulse amplifiers is greater than one, and said predetermined number of conductors is at least one, the common element of each of said amplifiers being commonly coupled to the second terminal means of each of the predetermined number of conductors, the conductors of the preselected number of conductors associated with a respective amplifier being the conductors of each of the other of said preselected numbers of conductors associated with their respective amplifiers, said preselected number of conductors being at least one.

References Cited by the Examiner UNITED STATES PATENTS 2,784,396 3/1957 Kaiser 340347 2,831,985 4/1958 Eckert 30788.5 2,835,828 5/1958 Vogelsong 307-885 2,969,535 1/1961 Foulkes 340-347 3,174,055 3/ 1965 Clapper 307-885 3,185,858 5/1965 Flatten 30788.5

ARTHUR GAUSS, Primary Examiner. IRVIN SRAGOW, Examiner. R. C. BAILEY, S. D. MILLER, Assistant Examiners, 

1. AN ENERGIZING SYSTEM COMPRISING A CONDUCTOR THROUGH WHICH A CURRENT PULSE IS TO BE PASSED, AN ENERGIZING VOLTAGE SOURCE, A CONSTANT CURRENT PULSE AMPLIFIER, SAID CONSTANT CURRENT PULSE AMPLIFIER HAVING AT LEAST THREE ELEMENTS, ONE OF SAID ELEMENTS FUNCTIONING AS AN OUTPUT ELEMENT, ANOTHER OF SAID ELEMENTS FUNCTIONING AS A CONTROL INPUT ELEMENT, ANOTHER OF SAID ELEMENTS FUNCTIONING AS A COMMON ELEMENT, SAID OUTPUT ELEMENT BEING CONNECTED TO A GROUND REFERENCE THROUGH A FEEDBACK RESISTOR, MEANS FOR SELECTIVELY CLAMPING SAID CONTROL ELEMENT TO A CONDUCTION VOLTAGE LEVEL FOR DRIVING SAID AMPLIFIER INTO CONDUCTION, SAID ENERGIZING VOLTAGE SOURCE BEING APPLIED TO SAID COMMON ELEMENT THROUGH SAID CONDUCTOR THROUGH WHICH A CURRENT PULSE IS TO BE PASSED, SAID CONDUCTION VOLTAGE LEVEL BEING SELECTIVELY APPLIED TO SAID CONTROL ELEMENT COINCIDENTALLY WITH FOLLOWING THE APPLICATION OF SAID ENERGIZING VOLTAGE OF SAID ENERGIZING VOLTAGE SOURCE TO SAID COMMON ELEMENT, SAID CONDUCTION VOLTAGE LEVEL AND RESISTANCE VALUE OF SAID RESISTOR DETERMINING THE OUTPUT CURRENT LEVEL PASSING THROUGH SAID CONDUCTOR TO BE ENERGIZED.
 11. AN ENERGIZING SYSTEM COMPRISING A CONDUCTOR THROUGH WHICH A CURRENT IS TO BE PASSED HAVING A MAGNITUDE AND A DIRECTION WHICH IS COMMENSURATE WITH THE MAGNITUDE AND SIGN OF THE ANALOG OF BINARY CODED DIGITAL INFORMATION TO BE CONVERTED, A FIRST AND SECOND ENERGIZING VOLTAGE SOURCE, AND FIRST AND SECOND GROUPS OF PLURAL CONSTANT CURRENT PULSE AMPLIFIERS, EACH GROUP CORRESPONDING IN NUMBER TO THE NUMBER OF ORDERS OF SIGNIFICANCE IN THE BINARY DIGITAL INFORMATION TO BE CONVERTED, SAID CONDUCTOR HAVING A FIRST AND SECOND EXTREMITY, AND PLURAL DECOUPLING DIODES, SAID FIRST ENERGIZING VOLTAGE SOURCE BEING CONNECTED TO SAID FIRST EXTREMITY OF SAID CONDUCTOR THROUGH A DECOUPLING DIODE, SAID FIRST GROUP OF CONSTANT CURRENT PULSE AMPLIFIERS BEING CONNECTED TO SAID SECOND EXTREMITY OF SAID CONDUCTOR THROUGH DECOUPLING DIODES, SAID SECOND ENERGIZING VOLTAGE SOURCE BEING CONNECTED TO SAID SECOND EXTREMITY OF SAID CONDUCTOR THROUGH A DECOUPLING DIODE, SAID SECOND GROUP OF CONSTANCE CURRENT PULSE AMPLIFIERS CONNECTED TO SAID FIRST EXTREMITY OF SAID
 14. AN ENERGIZING SYSTEM COMPRISING: A PREDETERMINED NUMBER OF CONDUCTORS THROUGH WHICH CURRENT PULSES ARE TO BE SELECTIVELY PASSED, EACH OF SAID CONDUCTORS HAVING FIRST AND SECOND TERMINAL MEANS; FIRST SELECTABLE ENERGIZING VOLTAGE SOURCE MEANS FOR SELECTIVELY APPLYING A FIRST ENERGIZING VOLTAGE TO THE FIRST TERMINAL MEANS OF SAID CONDUCTORS; AND A PREDETERMINED NUMBER OF CURRENT PULSE FIRST AMPLIFIERS, EACH OF SAID AMPLIFIERS HAVING AT LEAST THREE ELEMENTS, ONE OF SAID ELEMENTS FUNCTIONING AS A CONTROL INPUT ELEMENT, ANOTHER OF SAID ELEMENTS FUNCTIONING AS AN OUTPUT ELEMENT, ANOTHER OF SAID ELEMENTS FUNCTIONING AS A COMMON ELEMENT, SAID COMMON ELEMENT BEING COUPLED TO THE SECOND TERMINAL MEANS A PRESELECTED NUMBER OF SAID PREDETERMINED NUMBER OF CONDUCTORS, SAID OUTPUT ELEMENT BEING COUPLED TO A GROUND REFERENCE THROUGH A FEEDBACK RESISTOR, AND MEANS FOR SELECTIVELY CLAMPING THE CONTROL ELEMENT TO A CONDUCTION VOLTAGE LEVEL FOR DRIVING THE AMPLIFIER ASSOCIATED THEREWITH INTO CONDUCTION, SAID ENERGIZING VOLTAGE BEING SELECTIVELY APPLIED THROUGH SAID PRESELECTED NUMBER OF SAID PREDETERMINED NUMBER OF CONDUCTORS TO SAID COMMON ELEMENT, AND SAID CONDUCTION VOLTAGE LEVEL BEING SELECTIVELY APPLIED TO SAID CONTROL ELEMENT COINCIDENTALLY WITH AND FOLLOWING THE APPLICATION OF SAID ENERGIZING VOLTAGE TO SAID COMMON ELEMENT, SAID CONDUCTION VOLTAGE LEVEL AND RESISTANCE VALUE OF SAID RESISTOR DETERMINING THE OUTPUT CURRENT LEVEL PASSING THROUGH THE PRESELECTED NUMBER OF SAID PREDETERMINED NUMBER OF CONDUCTORS SELECTIVELY ENERGIZED BY SAID ENERGIZING VOLTAGE SOURCE MEANS AND THE CURRENT AMPLIFIER ASSOCIATED THEREWITH. 